An engine with .20 oversize bores is stamped with the letter A on the model pad of the block.

An engine with .001 undersize bearing shells is stamped with a maltese cross on the model pad of the block.

All engines except 273 and 318 cu.in. with .010 undersize bearing shells are stamped with a maltese cross followed by a letter X on the model pad.

273 and 318 cu.in. engines with .010 undersize bearing shells are stamped with the letter B suffixed to the engine serial number.

Engines with oversize tappets are stamped with a diamond and the number of the tappet
bore that is oversize on the model pad.

Cylinder heads using .005 oversize valves are marked O/S on the end of the head on the untapped boss for 361 and 383 cu.in engines, and on the front of the head of the
thermostat boss for the 170 and 225 cu.in. engines.

318 cu.in engines with .005 o/s valves are stamped X on the machine surface on each end of the cylinder head. A letter I for intake and a letter E for exhaust valve is steel stamped on the broached cylinder head boss above the exhaust port adjacent to the o/s valve.

273 cu.in. engines with .005 o/s valves are steel stamped X on the machined bosses on each end of the cylinder head. The broached cylinder head bosses adjacent to the center and two end lower now bolt holes are stamped to identify the o/s valves as follows: end bosses I signifies intake. E signifies exhaust. Center boss: IR signifies right intake. IL signifies left intake.ER signifies right exhaust. EL signifies left exhaust.